Method of sifting



P. NAEI -IER METHOD OF SIFTING Sept. 22, 1942."

4 Sheets-Sheet 1 Filed Aug. 2, 1940 Sept-22,1942. P. NAE'HER 2,296,293

METHOIS OF SIFTING Filed Aug. 2, 1940' 4 Sheets- Sheet 2 P P. NAEHER 2,296,293

- METHOD OF SIF'ItING Filed Aug. 2, 1940 4 ShQets-Sheet 3 Pietra Se t. 22, 1942 PATENT OFFICE Paul fiaeherxitvanston, 111., assignor B. F. Gump 00., Chicago, 11L, a corporation orn- .linois Application August 2, 1940, Serial No. 349,918 -2 claims. (01. zoo-ass) The present invention relates in general to a gyratory sifter and is mor particularly concerned with the improvements therein for increasing the capacity and efficiency thereof.

Heretofore, in some types of rotary ifters it 5 has been the practice to use cleaners on the bottom only of the sieveor bolting cloth, while in others it has been the general practic to utilize cleaners on the top only of the sieve or bolting cloth. in

In the type using bottom cleaners, small cleaning devices were usually confined for movement within limited areas below the sieve or bolting :Qcloth, these devices usually having tufts of bristles or were small pieces of cotton belt frayed on each end-arrangedto engage and sweep the under surface or the cloth during the sifting operation.

. Rubber balls have also been used for such purpose. On the other hand, in the type having top cleaners: locust seeds, coffee beans, wheat and the like were utilized as the cleaning instrumentalities, these being supplied with th material to be sifted to the upper surface of the sieve or boita ing cloth to travel with the material over the upper surface of'the sieve andbe discharged with the tailings from which they were separated in some suitable manner and returned to the head end of the sifter where they were again mixed with the materials being bolted.

mentalities coact to increase the bolting capacity of the sieve or bolting cloth by simultaneously cleaning both its upper and under surfaces.

It is a further object of the present invention to provide an improved sifter apparatus construction to increase the capacity and efllciency of the sieve or bolting cloth utilized therein.

It is also an object of the invention to provide improved supporting means for the sieve housing.

Another object of the herelndescribed invention is to provide sifter apparatu embodying a novel driving arrangement.

Still another object is to provide a novel method forsifting material which may bev practiced by the utilization of my improved apparatus.

Other objects and features of the invention will more fully appear from the following detailed description taken in connection with the accompanying drawings which illustrate a preferred embodiment thereof, and in which:

a Figure lis a top plan view of a sifter con-. structed according to the present invention, a portion of the cover thereof being cut away to disclose the interior constructioniadiacent this end of the sifter;

Figure 2 is a longitudinal section through the same, taken substantially on line II--II of Figure 1;

Figure 3 is a transverse sectional view through To my knowledge, the two arrangement de- 80 the same adjacent the outlet end for the bolted scribed above have always been utilized separately and insofar as I am aware there ha notuntil my present invention been anyattempt to coordinate the two arrangements'in a single sifting apparatus so as to secure the added benefits re- :5

suiting from'the simultaneous cleaning of both the upper and lower surfaces of the bolting cloth. It has been discovered that by. utilizing a double cleaning arrangement with cleaning instrumentalities acting simultaneously upon both the up- 40 per and under surfaces of the sieve or bolting cloth, the sifting capacity per square foot of bolting surface is materially increased over its capacity' when only-one of its surfaces is being cleaned? i romtests which have been conducted on sifters utilizing my improved double cleaning v arrangement, this increase has been shown to be as much as approximately thirty-five per cent over the capacity obtained when utilizing cleaners only on the under side of the sieve or bolting 60 .cloth.

, It is a primary object of the hereindescribed invention to provide improved sifter apparatus embodying a novel cleaning arrangement for the material, taken substantially on line III-III of Figure 2;

Figure 4 is a plan view of the sitter with the the bolting cloth or sieve;

Figure 5 is a transverse sectional view showing the lowerbolting cloth or sieve and the connection therefrom to elevating means for the cleaning instrumentalities for the upper surface of the bolting cloth or sieve; t I

Figure 6 is an enlarged fragmentary sectional view showing details of the elevating means for the objects utilized for cleaning the upper surface of the bolting cloth or sieve, taken substantially onlineVI-VIofhlgured;

Figure 7 is a fragmentary sectional view showing the arrangement of additional screens below the bolting cloth or sieve and the disposition of the cleaning devices for the under surface of the v bolting clothor sieve; and

Figure 8 is a fragmentary view looking down sieve or bolting cloth, wherein cleaning instruupon the sifting instrumentalltles, the bolting cloth or sieve, first screen and second screen therebelow being successively cut away and showing a cleaning device for the under surface of the bolting cloth or sieve as it appears in plan view.

As shown on the drawings:

For illustrating th present invention, I have shown in the drawings an apparatus for sifting, screening or bolting flourfor separating the same according to its particle sizes. -The particular construction shown in the drawings is by way of example of one construction embodying the invention, and it is not intended to limit this inven tion to the particular construction or form of sitter shown. v V

.The present invention may be utilized with sifters employing sieves or screens of any suitable or desired construction and any desired number of such sieves may be employed and arranged to provide' the desired number of separations and pasess of the material to be sifted.

with an outlet opening 33 by means of which the sifted or bolted material may be conducted from the outlet compartment 32.

Referring to Figures 2 and 3, each sifting compartment has disposed therein 'a bolting cloth or More specifically, the illustrated construction comprises a sieve or screen housing, as generally indicated at ID, of the usual rectangular construction. This housing is supported above a fixed base structure II by means of four wobble posts l2 which are arranged in quadrature.

Each wobble post is connected at its lowermost end through a universal joint l3 to the base structure and at its uppermost end through a universal joint ll to the bottom of the housing. As clearly shown in Figures 2 and 3, the base structure also has supported thereon the driving mechanism for the sitter. For this purpose there is provided substantially at the center of the base structure a bracket ii for supporting a vertically disposed bearing it which has rotatably mounted therein a shaft ll. Fitted to the uppermost end of this shaft is a suitable flywheel it which carries an oil-center bearing 69 that forms a journal box for a center pin 20 which is part of spider 2| fastened to the sifter housing. With such an arrangement, a circular or gymtory movement is imparted to the sifter housing during operation of the sifter.

At one side of the base structure there is provided a driving motor 22 which is supported upon a suitable angle bracket 23 with its driving shaft extending vertically and carrying at its uppermost end a suitable driving pulley 24, this pulley being connected through a suitable flexible connection such as a belt 25 with the flywheel l8. It will be noted that this arrangement provides a direct connection between the motor and flywheel and dispenses with the use of speed changing gears and other complicated driving mechanism. In operation, driving of the flywheel imparts a gyratory movement to the housing, this movement being permitted by the off-center bearingand centerpin and through the use of the previously described universal joints in the wobble post construction.

The top of the sifter housing is provided with a suitable cover 29 which is provided centrally at one end with an opening 21 for the admission of material to be sifted therein. As shown in Figures 1 and 3, the interior of thehousing is separated transversely into separate compartments by means of a longitudinally extending partition 29, each of these compartments being equipped with one or more bolting cloths or sieves for sifting the material supplied thereto. The material entering the inlet 21 is divided into two portions by the uppermost edge of the partition 28 which extends diametrically across the opening 21. The partition 28 cooperates with sieve 34 which is supported on a suitable frame construction and which is downwardly inclined from the inlet end of the housing toward the outlet end, the sieve 34 be g terminated inwardly of the end wall of the housing at the outlet end thereof so that the tailings from the sieve 34 may be discharged into the upper end of compartment 32. The sieve 34 may be of any suitable material such, for example, as a silk I cloth, such a cloth of suitable fineness being satisfactory when bolting flour. Spaced below the bolting cloth 34, there is provided a double screen which is preferably composed of an upper coarse screen 35 and a lower finer screen 36. For such purpose, an upper screen of No. 3 mesh and a lower screen of No. 8 or 10 mesh have been found satisfactory, v

Below the sifting unit just described, there are provided suitable drift boards 31-3! which are laterally downwardly inclined from the partition 28 to the side walls 29 wherematerial falling upon the drift boards may be conducted through suitable openings 38 into the passageways 39. Thus the material which is bolted or sifted by the upper sifting unit will pass into the collecting compartment 3|, while tailings from the sieve 34 will pass into the compartment 32 and drop onto a second or lower sifting unit which is in-' clined in the opposite direction from the first unit and composed of the bolting cloth or sieve 34, the coarse screen 35' and the fine screen 36. At the right end of the sifter as viewed in Figure 2, it will be noted that the second sifting unit extends across the compartment 32 so that tailings from the upper sieve unit will not be conducted into the outlet from the bolted or sifted material. At the opposite end of the lower sifting unit, there is provideda compartment 38 which is defined by one end of the housing and an inwardly spaced partition member 39. The compartment 38 communicates at its bottom with an outlet 40 through which the tailings may pass and be collected in any desired manner. At its uppermost end, the compartment 38 is closed by a screen 39', preferably of approximately No. 8 or 10 mesh, this screen being so chosen as to permit the passage of the tailings therethrough but oppose passage of locust seeds, coffee beans, wheat and the like, as shown at 40', which may be utilized as a cleaning instrumentality for the sieve as will hereafter be explained. I

Below the lowermost sieve unit in the collecting compartment there is provided a drift board 4| which extends across the housing below the laterally disposed passages 39-39'and also the sifting compartments so as to'receive the sifted material from the drift boards 3'!-3| under the upper sieve and also the sifted material from the lowermost sieve. The drift board ll is inaacaaea j sifter housing and is arranged to discharge sifted 'materi'al into the lowermost end of compartment 32 below'the portion of the lower siftingunit extending thereinto.

while I have shown an arrangement with two sieves, in this instance two it will be appreciated that more sieves may be provided where desired to increase the capacity Also, as many separations as desired may be provided for by using sieves with different meshes of silk or wire bolting cloth, and arranging the flow and outlet channels accordingly.

For the material in its movement over the sieves or bolting cloths, suitable flights '42 have been shown along one of the walls 29 and the partition 28 above the upper sieves. Similar flights may in a like manner be associated with the lower sieves, if found necessary.

It has been found in operating sifters, that flour and soft materials have a tendencyto paste or clog the meshes of the bolting cloth, and that the cleaner or more open the meshes are kept, the more eflicient the bolting or sifting will be.

In my improved apparatus, provision has been made for cleaning the bolting cloth or sieve on both its upper and lower surfaces during the operation of the sifter.

For cleaning the upper surface, locust seeds, coifee beans, wheat or similar objects are introduced into the material being supplied to, the sifter onto the upper surface of the sieves. These objects moving along with the material to be sifted in an even and regulated amount over the'upper surface of the sieve provide a rubbing action which greatly facilitates the pas sage of the material through the bolting cloth or sieve and prevents to a large extent its becoming occluded. These. objects pass onto the lower sifting unit with the tailings from the upper sifting unit. and since these objects are of such size that they will not pass through the screen at the upper end of the compartment 38, the objects will tend to accumulate at the bottom of a tubular 43 at the outermost vcomers of the sifting compartments at the head.

end of the Openings 43{ as shownin Figures 5 and 6 are provided in the walls" at the bottoms of the; tubular passages 43 to admit the objects thereinto. Disposed within each'of the passages 43, there is provided a spiral screw or ramp'44 which leads to a collecting container 45 ,atthe' top of each sifting compartment of the apparatus above the first sifting unit. The objects may pass from the container 45 autobe discharged with the bolted material.

hole become worn in it, these particles and objects could pass through the coarse screen and While these objects and particles thereof were not of such a nature as to endanger the health of those utilizing the bolted product, nevertheless their matically through a hinged door 48 so as to again enter and comingle with the material being supplied to the sifter. Due to the gymtory movements of thesifter housing, the ob- Jects will be caused to be automatically moved up the spiral ramp and elevated from the botportionto the top portion of the sifter and thus continuously circulated over the upper surfaces of the bolting cloths or sieves with the material being V In apparatus of this type as previously constructed, it has been the custom to provide asingle screen below the bolting cloth or sieve.

'This screen was usually of coarse construction and in the event that any particles should break off from the locust seeds, coffee beans, wheat or other objects being utilized to clean the upper surface of the bolting cloth or sieve, or. if the bolting cloth or sieve should become torn or a presence in the bolted material tended to produce a lower quality product. In order to prevent the passage of either the objects or particles thereof into the finished product, I have provided a finer. screen, in this instance the screens 36 and 36' which will effectively prevent the passage of the objects or. particles into the finished product and consequently enhance the quality of the same.

In order to cleanthe under surface of the bolting cloth or sieve, I have provided cleaning devices as shown in Figures '1 and 8 in detail. In generaLthese devices comprise members 41 which may be molded or otherwise formed from any suitable material in the shape of a figure 8. One of the loops as shown at 48 is larger than the other as shown at 49. These two loops are connected by abridging portion 50, and the loop 48 is preferably of flat or plain construction while the smaller loop 49 is offset as shown in Figure '1. At thebridging portion of the member, there is provided a rounded protuberance 5! which may be the head of a rivet having a bifurcated shank portion which extends through a suitable opening in the bridging portion 50. The ends of the shank of the rivet may be spread apart to securely hold the rivet in position. The head of this rivet forms a fulcrum upon which the member 41 may turn, slide and be rocked to cause the loop 48 and 49 to rub and tap against the under surface of the bolting cloth or sieve during the gyratory movement of the sifter housing. Moreover, these cleaning devices will move at random and continuously strike the undersurface of the bolting cloth at different points during the operation of the apparatus.

It will be noted that this tapping action tends to vibrate the bolting cloth transversely and I move it in a direction against the direction of It has been found that by combining the rub- I bing and tapping action of the cleaning devices 41 with the cleaning action of the objects such as locust seeds, coffee beans, wheat or the like, which may be supplied to the top surface of the bolting cloth, the sifting capacity of the bolting cloth or sieve is materially increased over that which would be obtained when the bolting cloth is cleaned only on one side.

As shown inFigure 7, the cleaning devices 41 are positioned between the bolting cloth and the screens disposed therebelow and the devices are supported on the uppermost of the screens over which the devices will be automatically moved during the operation of the apparatus.

It is thought that my improved sifting method will be readily apparent from the foregoing description of the apparatus by means of which the method may be practiced.

From the foregoing description, it will be apparent that the present invention provides an improved sifter apparatus and novel method of sifting, the. apparatus embodying a novel cleaning arrangement for the sieve or bolting cloth, wherein cleaning instrumentalities coact to increase the bolting capacity of the sieve or bolting cloth by simultaneously cleaning both its upper and under surfaces; apparatus of the hereindescribed type having increased capacity and efliciency; which incorporates improved supporting means for the sieve housing: which is provided with a novel driving arrangement: and which utilizes a simple and eflective construction in which increased sifting capacity may be I obtained and a high quality product produced.

It is, of course, to be understood that although I have described in detail a preferred embodiment of my invention, the invention is not to be thus limited, but only insofar as defined by the scope and spirit of the appended claims.

I claim as my invention:

1. The method of sifting flour in a shakin type of sieve which comprises placing upon the upper surfaceof a sieve the flour to be sifted,

introducing a plurality of freely movable small objects of a size considerablylarger than the flour particles and having a density equal to or greater than that of the flour particles into the flour for cooperating with the upper surface of.

the sieve to subject particles of the flour and the sieve to a rubbing action to force particles of flour through the sieve, removing tailings and objects from the top of the sieve, separating said objects from any tailings and continuously returning said objects to the top of said sieve, and simultaneously therewith transversely tapping the under surface of the sieve at a plurality of points to jar the sieve and movable objects I thereon the interstices of the sieve and to enhance the thus aiding in freeing particles clogging action of the freely movable objects in rubbing particles through the sieve wherebyflthe aggre-' gate of flour passing through the sieve is substantially greater than that attained by the use separately of said rubbing and tapping actions.

2. The method of sifting flour in a vibratory type of sitter, which method comprises placing upon the upper surface .of a bolting sieve the flour to be sifted, introducing into the flour a plurality of freely movable small objects of a size considerably larger than the flour particles neath the bolting sieve, thereby aiding in free-' ing the flour particles from the bolting sieve and enhancing the action of the rubbing objects.

PAUL NAEHER. 

